Gear train control arrangement



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I indication by frictionally braking the drive means.

United States Patent l 3,251,544 GEAR TRAIN CONTROL ARRANGEMENT Werner Pilz, Schwenningen, and Wilhelm Haupt, Villingen, Germany, assignors to Kienzle Apparate G.m.b.H.,

Villingen, Black Forest, Germany Filed Got. 13, 1964, Ser. No. 403,540 Claims priority, application Germany, Oct. 18, 1963,

K 46,016 Y 2 Claims. (Cl. 23591) The present invention relates to a gear train control arrangement and more particularly to an arrangement for controlling the relative angular position of the gears of a gear train by which the number wheels of the register of a calculator or meter are driven.

When the first gear of a gear train is driven in one direction, the teeth of the meshing gears abut each other in the direction of the transmission of force and have play in the opposite direction. When a number wheel of a register is driven by the last gear of the train, and the drive is suddenly stopped, the gears and the number tend to turn further in the previous direction or as far as the play will permit until the teeth of the meshing gears abut each other again. As a result, the indicating position of the stopped number wheels is not exactly the same position as during the drive of the number wheels through the gear train.

Particularly, when rapidly running with large number wheels or indicator drums are suddenly stopped, the large rotating masses have accumulated a substantial amount of kinetic energy so that all gears are angularly displaced relative'to each other by the number wheel turning further due to inertia whereby the play of all gears is added and represented in the angular displacement of the number wheel which may correspond to several measured units.

It has been proposed to eliminate this inaccuracy of A certain improvement is achieved in this manner, but the braking has the disadvantage that a rapid operation of the meter requires a strongbraking force which is added to the load of the drive means, and in many cases exceeds the permissible limit.

It is one object of the present invention to overcome the disadvantages of known gear train arrangements for the number wheels of a meter or calculator, and to control the gear train in such a manner that the number wheel assumes a correct position after the drive is suddenly stopped. It is another object of the present invention to control a gear train in such a manner that gears which have been angularly displaced relative to each other when the gears are stopped are turned back to the relative position which the gear had While they were driven.

It is another object of the invention to return a number wheel which has moved to far due to inertia 'to a correct position by means which do not constitute a substantial additional load on the drive means.

Another object of the invention is to return a gear of a gear train, or a number wheel driven by the same, to the same angular position the 'gear or number wheel had when the drive means of the gear train was stopped.

With these objects in view, the present invention relates to an arrangement for controlling the relative position of the gears of a gear train, such as is used for driving the number wheels of a register of a meter or calculator. In accordance with the invention, the drive means drives one of the gears of a series of machine gears so that during rotation in one direction the teeth of the gears abut each other in the direction of the transmission force and have play in the opposite'direction.

In accordance with the present invention, resilient means are provided which are tensioned during rotation 3,251,544 Patented May 17, 1966 of the drive means so as to turn a gear or number wheel back when the same has moved due to inertia too far when the drive means is suddenly stopped.

In one embodiment of the invention, the resilient means has at one end a coupling portion in frictional contact with a gear which drives the number wheel, or with'the number wheel itself, while the other end of the resilient means is secured to a stationary part. In this manner, the resilient means, preferably a coil spring, is tensioned during rotation of-the gear train with the number wheel, and turns the gears and the number wheel back to the correct position after the drive means has stopped.

In another embodiment of the invention, the resilient means is a spring frictionally engaging a stationary part at one end, and having the other end secured to the rotating gear or to the number wheel so that the spiral spring is tensioned during rotation of the drive means and gears with the number wheel. When the drive means is suddenly stopped, and the number wheel and the gears move further due to the play between the gears, the number wheel and the gears are turned back to the correct previous position when the spiral spring returns to the untensioned position.

During the rotation of the gear train with the number wheels, the resilient means continuously counteracts the drive since it is tensioned by the frictional coupling. The

friction. force is selected by suitably designing the partsso that the resilient means is tensioned just sufficiently with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary elevation, partly in section on line 1-1 in FIG. 2, and illustrating a first embodiment of the invention;

FIG. 2 is an axial sectional view taken along line IL-11 in FIG. 1;

FIG. 3 is an axial sectional view taken along line IIIIII in FIG. 4 and illustrating another embodiment of the invention; and

FIG. 4 is an elevation, partially in section taken on line IVIV in FIG. 3.

Referring now to the drawings, and more particularly to FIGS. 1 and 2, the shaft 1 supports a set of number Wheels or indicator drums for turning movement, only one number wheel 2 being visible in FIG. 1. A gear 3 is secured to each number wheel of the register and meshes with another gear 4 meshing with a gear 5 driven by a drive shaft 6. Additional gears may be provided between gears 4 and 5 of the gear train 3, 4, 5, but are not shown for the sake of simplicity.

As best seen in FIG. 2, gear 4 is mounted by a pin 4a on shaft 7. A coupling part 3 having projections 9 engaging corresponding projections of another coupling part 10 which is mounted on shaft 7 for axial movement to and from the illustrated coupling position in which coupling parts 8 and it) are connected for rotation, Since coupling part 10 is secured by key 11 for rotation with shaft 7, coupling part 8 turns together with shaft 7 in the engaged position of coupling 8, 9, 10. Since gear 4 is secured to shaft 7, it turns together with coupling part 8.

Coupling 8, 9, 10 is operated during the clearing of the register, and for the purpose of the present invention, it could be assumed that coupling 8, 9, 10 is a solid bushing secured to shaft 7 since the spring 10a abuts disks Nb and gear 4 which is fixedly mounted on shaft 7 to hold the coupling in the illustrated engaged positron.

An angular member has a radial arm 12 mounted for angular movement on shaft 7 and another arm 13 projecting parallel to the axis of shaft 7 into the region of the part 8. A screw 14 is threaded into arm 13 and has a smooth free end passing through a bore in a part-circular coupling portion 15. A nut 19 is turnably mounted on the threaded portion of screw 14, and can be adjusted for varying the tension of a spring 16 by which coupling portion 15 is pressed against the rotary part 8. Coupling part 15 has a groove in which a lining 15a is located so that the rotary part 8 is not engaged by metal, but by lining 15a which consists of a material of the type used for brake linings and friction couplings.

A stationary part 18 is secured to a fixed frame part, not shown, by screws 18a, and elongated spiral spring 17 has one end secured to the stationary part 13, and the other end secured to member 12, 13. The resilient means 12 to 17 functions as follows:

. During a metering, totalizing or counting operation, drive shaft 6 rotates in counterclockwise direction so that gear 4 rotates in clockwise direction as indicated by an arrow. This rotary motion is transmitted to the number wheel 2 by gear 3. The rotary part 8 rotates with gear 4 and is frictionally coupled with the coupling portion 15, 15a. Consequently, coupling portion 15 will move together with rotary body 8 and gear 4 in clockwise direction so that member 12, 13 will turn in the same direction while spiral spring 17 is tensioned. As the tension of the coil spring increases, while the frictional coupling force between members 15a and 8 remains the same, a condition is reached where coupling portion 15 is no further turned and the length of the tensioned spring 17 remains the same. The angular displacement of coupling portion 15 and member 12, 13 during rotation of gear 4 can be adjusted varying the tension of spring 16 by means of nut 19 so that coupling portion 15 is pressed against the peripheral surface of the rotary part 8 with a different coupling force acting in radial direction in relation to shaft 7. During rotation of the gears of the gear train, the resilient means 12 to 17 will be in a tensioned position with coupling portion 15, 15a sliding on the rtary part g in a condition of equilibrium.

The leading flanks of the teeth of gear abut the trailing flanks of the teeth of gear 4, While there is play between the trailing flanks of gear 5 and the leading flanks of gear 4 during the counting operation of the register.

When the counting operation is suddenly stopped by stopping drive shaft 6, gear 4, gear 3 and number wheel 2 will not immediately stop since they tend to move on in the previous direction of rotation due to inertia.

Gear 4 will turn in the same clockwise direction as before to an angularly displaced position in which the trailing flanks of the teeth of gear 4 have play with the leading flanks of the teeth of gear 5, while the leading flanks of the teeth of gear 4 abut the trailing flanks of the teeth of gear 5. The angular relative displacement between gears 4 and 5 corresponds to the play between the teeth of gears 4 and 5, and if additional gears are provided in the gear train between gears 4 and 5, all these gears will be turned relative to each other so that the play of all gears will add up and be represented in an angularly displaced position of number wheel 2 which also has turned further in the previous direction of rotation due to the play between the teeth of gears 3 and 4.

As soon as number wheel 2 and gear 4 have stopped (in the angularly displaced position, there is no force any longer operative to tension spring 17 as during the rotation of the gears. Consequently, spring 17 moves to an untensioned position, turning member 12, 13 in counterclock-wise direction together with coupling portion 15, and since the same is still coupled with the rotary part 8, gear 4 is turned in counterclockwise direction until the teeth of gears 4 and 5 abut each other in the same position as during the drive of the number wheel through the gear train, and at the moment in which the drive was stopped.

In contrast to prior art constructions in which brake means are used for preventing a relative angular displacement between the last gears and the number "wheels and the drive gear, the present invention permits such angular displacement caused by inertia at the moment in which the gear train is stopped, but eliminates the angular displacement again by turning back the gears and number wheels which have moved too far in the moment of stopping due to inertia.

While in the prior art constructions, the drive had to supply the additional torque for overcoming the continuous effective brake, a much smaller additional load torque is produced by the frictional engagement between coupling portion 15 and rotary part 8 since the friction force is so small as to permit turning of gear 4 relative to coupling portion 15 by mere inertia.

The embodiment illustrated in FIGS. 3 and 4 operate on the same type of register and gear train as described with reference to FIGS. 1 and 2, and corresponding parts are indicated by like reference numerals.

The number wheels 2 of the register are mounted on shaft 1, and are secured to gears 3 meshing with gears 4 which are in meshing engagement with gears 5. Gear 4 is secured to the rotary part 8 of the coupling 8-11 which is secured to shaft 7 for rotation therewith. A coil spring 20 has an inner end fixedly secured to shaft 7 by a pin 20a, and an outer end sliding on an inner circular surface of a casing 22 which is stationary and secured to a frame wall of the apparatus. Consequently, the outer end of spring 20 is a coupling portion in frictional engagement with the stationary part 22, while the inner end of spring 20 is secured for rotation to rotary part 8 by shaft 7 and pin 20a.

While gear 5 drives the number wheels through gear 4 and gear 3, as described with reference to the embodiment of FIGS. 1 and 2, gear 4 rotates in clockwise direction as viewed in FIG. 4. Coil spring 20 is wound in clockwise direction so that during rotation of gear 4 with rotary part 8 and shaft 7, the inner end of coil spring 20 is more tightly coiled about shaft 7 so that the outer diameter of spring 20 is reduced and the pressure of the outer coupling end against the inner circular surface of the stationary casing part 20 is reduced so that only low frictional forces develop during the sliding of the outer end portion of spring 20 on the inner surface of the stationary casing part 22. As a result, the additional load torque which has to be provided by the drive means is negligible.

When the drive means is stopped and number wheel 2 moves further together with gear 4 in the previous direction of rotation until the play of the gear train is taken up, as explained with reference to the embodiment of FIGS. 1 and 2, the tensioned spring 20 uncoils and turns gear 4 in counterclockwise direction to the previous position in relation to gear 5. If additional gears are provided between gears 4 and 5, the play of the several gears are added up to cause a greater angular displacement of the number wheels when the drive is stopped, but spring 20' turning back to a less tensioned position will turn all gears until the relative position between the gears at the moment of stopping of the drive is again assumed by the gears. The flanks of the gear teeth which abut each other in the driven condition of the gear train, are again in engagement after resilient means 20' has turned back to a less-tensioned position.

It will be understood that each of the elements described above or two or more together, may also find a useful application in other types of gear control arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in a resilient means frictionally coupled to a gear of the gear train by which a number wheel of a register is driven, it is not intended to-be limited to the details shown, since various modification and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. In a register, in combination, a gear train including a series of meshing gears having gear teeth with play between each other; a drive means for driving one of said gears; a number wheel driven by another of said gears so that during rotation of said drive means in one direction said teeth abut each other in the direction of transmission of force; a rotary part fixed to said other gear for rotation therewith; a member having an inner portion mounted for turning movement about the axis of said other gear and an outer portion; a coupling portion mounted on said outer portion and adapted to frictionally contact said roing an adjustable screw mounted on said member and having a portion received by a bore of said coupling portion, a nut mounted on said screw, and a spring between said nut and said coupling portion adjustable by operation of said nut for spring-loading said coupling portion; a stationary part; and a spring connecting said stationary part with said member and being tensioned during rotation of said drive means in said one direction while said coupling portion slides on said rotary part, said other gear and said number wheel turning by inertia due to said play further through a small angle upon stopping of said drive means so that said spring, moving to a less tensioned position, turns said other gear back to a position in which said teeth abut each other in said direction of transmission of force.

2. The combination claimed in claim 1 wherein said other gear and said rotary part are secured to each other, including a shaft supporting said other gear and said rotary part for turning movement, and wherein said member has a hub mounted on said shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,044,926 v 6/1936 Welch etal 235144 2,059,341 11/1936 Harvell et a1. 235-144 LOUIS J. CAPOZI, Primary Examiner.

LEO SMILOW, Examiner.

tary part; biasing means for said coupling portion includ- C. G. COVELL, I. G. MURRAY, Assistant Examiners. 

1. IN A REGISTER, IN COMBINATION, A GEAR TRAIN INCLUDING A SERIES OF MESHING GEARS HAVING GEAR TEETH WITH PLAY BETWEEN EACH OTHER; A DRIVE MEANS FOR DRIVING ONE OF SAID GEARS; A NUMBER WHEEL DRIVEN BY ANOTHER OF SAID GEARS SO THAT DURING ROTATION OF SAID DRIVE MEANS IN ONE DIRECTION SAID TEETH ABUT EACH OTHER IN THE DIRECTION OF TRANSMISSION OF FORCE; A ROTARY PART FIXED TO SAID OTHER GEAR FOR ROTATION THEREWITH; A MEMBER HAVING AN INNER PORTION MOUNTED FOR TURNING MOVEMENT ABOUT THE AXIS OF SAID OTHER GEAR AND AN OUTER PORTION; A COUPLING PORTION MOUNTED ON SAID OUTER PORTION AND ADAPTED TO FRICTIONALLY CONTACT SAID ROTARY PART; BIASING MEANS FOR SAID COUPLING PORTION INCLUDING AN ADJUSTABLE SCREW MOUNTED ON SAID MEMBER AND HAVING A PORTION RECEIVED BY A BORE OF SAID COUPLING PORTION, A NUT MOUNTED ON SAID SCREW, AND A SPRING BETWEEN SAID NUT AND SAID COUPLING PORTION ADJUSTABLE BY OPERATION OF 